88 



ments or basalt, which last is not found solid in any place in 

 the neighbourhood, we may conclude that these, together with 

 a corresponding amount of the granite, have been conveyed 

 hither by ice, while the chief mass of the granite has origi- 

 nated in the solid rocks of the immediate neighbourhood. It 

 has been proved in this way that in none of the samples 

 can a greater part than about Vs or Ve be supposed to 

 originate from the ice , this is stated in reference to the 

 samples that were found nearest land; with regard to the 

 others , it is impossible to state anything with corresponding 

 accuracy. 



3) The third source of those mentioned above from which 

 the deposits may have derived material is the moraines , or 

 other ice-deposits at the bottom of the sea. Such deposits 

 can sometimes be obtained directly by aid of the sounding- 

 tube , in which case we have not to do with a true sea-floor 

 deposit. In the case of moraine-derived material we must 

 suppose that deposition at the bottom of the sea took place 

 exceedingly slowly, and near land we cannot suppose that such 

 could be the case, while at a greater distance from land it will 

 appear more Ukely. If moraine-ridges are left at the bottom of 

 the sea from the ice-age , there is some probability that they 

 may be quite uncovered by later deposits for their greater 

 height in proportion to the surrounding territory will generally 

 cause a fairly strong current to run above them, so that the 

 finer ingredients which generally form the greater part of 

 the deposit cannot be laid down. If, on the contrary, the mo- 

 raine material is not found at any specially great height, the 

 whole tract will propably have been covered over since the 

 ice-age by a thin layer of deposits through which large 

 quantities of ice-borne pebbles may project, and these later 

 oil by their disintegration will produce material for the 

 samples. 



